NTSB Identification: WPR10LA171
14 CFR Part 91: General Aviation
Accident occurred Thursday, March 18, 2010 in Arlington, WA
Probable Cause Approval Date: 07/18/2011
Aircraft: CARR RV-4, registration: N66PB
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The pilot said that when he took off and retracted the airplane's landing gear, only the tailwheel retracted. He lowered the landing gear and saw three green lights, indicating that all three landing gear were down and safe for landing. He then proceeded to his destination with the main landing gear down. During landing rollout at his destination, the left main landing gear collapsed. The airplane departed the left side of the runway before the right main landing gear collapsed as well. When the left wing's main landing gear collapsed outward, it damaged the wing structure and punctured the left fuel tank. The skin on the top of the right wing and the right aileron were wrinkled. Postaccident examination of the landing gear revealed that both main landing gear drag link bolts failed. These bolts were welded to the back of each main landing gear as part of their landing retraction system. Examination of photographs of the broken bolts by an NTSB metallurgist revealed that each bolt exhibited cantilever beam bending in overstress. The quality of the photographs was inadequate to determine if fatigue played a role.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The failure of both main landing gear's drag link bolts in overstress and the subsequent collapse of the landing gear during landing rollout.

Full narrative available

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